Use CRLF as EOL (#3566)

* Use CRLF as EOL

GenerateMetadataFromCSUnitTest.cs and possibly more assume their EOLs are
CRLF.

* Limit the length of revision string

The release note of Git 2.11.0 says:
> * The default abbreviation length, which has historically been 7, now
>   scales as the repository grows, using the approximate number of
>   objects in the repository and a bit of math around the birthday
>   paradox. The logic suggests to use 12 hexdigits for the Linux kernel,
>   and 9 to 10 for Git itself.

However, special version string cannot include too long values. This change
limits the length to 7, the number traditionally used.

.gitattributes

@@ -0,0 +1,2 @@
+* text=auto eol=crlf
+*.sh eol=lf

.gitignore

@@ -34,7 +34,6 @@ target/
 *.sln.ide
 *.cache
 *.sln.metaproj
-.gitattributes
 .settings
 log.txt
 debugSettings.json

build.ps1

@@ -136,7 +136,7 @@ if ($prod -eq $true) {
     $assemblyVersion = (($version + '0') -join '.').Substring(1)
     $assemblyFileVersion = (($version + $revision) -join '.').Substring(1)
     if ($branch -ne $releaseBranch) {
-        $abbrev = $commitInfo[2]
+        $abbrev = $commitInfo[2].Substring(0, 7)
         $packageVersion = ((($version -join '.'), "b", $revision, $abbrev) -join '-').Substring(1)
     }
     else {